One known example of a gripping mechanism or robot hand configured to grip balls and other objects using a pair of left and right gripping implements is one having a mechanism for converting drive force from a drive source into the opening and closing movements of the left and right gripping implements via a link mechanism. Patent Document 1 discloses a gripping device in which the movement of a linearly moving cylinder rod is converted via a link mechanism into movement for opening and closing the final left and right links.
[Patent Document 1] JP-A 2000-218583
In order for an object to be gripped or held by the final left and right links in a gripping mechanism or robot hand using a link mechanism, the torque applied to the links is controlled according to the opened or closed positions of the links in order to control the gripping force or holding force applied to the links. However, it is difficult to control the torque applied to the links so as to obtain the appropriate object-gripping force or object-holding force according to the opened or closed positions of the links, and the object-gripping force or object-holding force cannot be accurately adjusted.
Particularly in cases in which a flexible object is gripped, the object is compressed and deformed by the links; therefore, with only torque control based on link position control, it is difficult to implement control for gripping or holding a flexible object without compressing the object. In cases of gripping an object made of a fragile material, there is a danger that the object will be damaged. Furthermore, with only torque control based on link position control, there is a limit to the size of the object that can be gripped or held by an appropriate gripping force or holding force.